I'd like to lose some fat.

My local gym said that 'high intensity' running was useless, as it doesn't burn any 'fat calories' whatsoever.
I was told that I'd only burn 'fat calories' if I exercised at a much 'lower intensity'.

However, a couple of books that I've read say that what the gym told me was a misconception. One book quoted the following example:-

'High intensity' half-hour run:-

Total calories - 600;
Percentage of fat calories - 40%
Fat calories (600 x 0.4) - 240

'Low intensity' half-hour run:-

Total calories - 300
Percentage of fat calories - 70%
Fat calories (300 x 0.7) - 210

As you can see, the percentage of 'fat burning' calories is greater on the low intensity run. However, the total number of calories to which this percentage is applied is of course much fewer, meaning that fat calorie consumption is lower than with high intensity runs.

Who should I believe - the gym or the books?



  • From personal observation the best way I have noticed myself and some of my friends lose weight (fat) is by walking 40mins to 1.5 hrs every day in total.

    This basically consists of walking to and from work 5 days a week.
  • Pammie*Pammie* ✭✭✭
    Is that in one go or throughout the day
  • Lightning,

    As someone who is shifting 3-4lbs a week currently, I have asked the same questions.

    Personally I go for the low intensity option. The equation you quoted missed a crucial detail - you can't do high intensity runs every day!

    The key (or, rather, one of them) to "turning on" your fat burning mechanism is the consistency of regular low intensity exercise.
  • Lightening - As far as I am aware, those formulae that you have quoted above appear to be correct. At the higher intensity, a lot of the calories burnt are glycogen calories.

    Heres the crux.

    With the 30mins high intensity, ur body's metabolism will remain a good bit higher than with the low intensity for a long time after the exercise. So in other words, the formula above gives 240kcal (fat) for high intensity. Overall, this will be a good bit higher if you take into account the increased metabolism.

    So in short, you will shift more fat with high intensity workouts, but TAKE AT LEAST A DAY OF REST (or low intensity/recovery workout) BETWEEN HIGH INTENSITY WORKOUTS so that your body can recover the lost glycogen.
  • btw, just noticed that the formulae above do not take into account your body weight. This will affect the actual result but it is correct in theory.
  • Not convinced RR! What you say is true as far as it goes, but that does not mean it is the best way to lose fat LONG TERM.

    The best thing to do is to teach your body to naturally burn as much fat as possible at higher and higher speeds. That HAS to be done by LOWER intensity running.

    Your sums are right when looking at a day or a week, but that is not the issue at hand.
  • No - the books are right. Also, doing some resistance work will help you develop more lean muscle tissue and therefore turn you into an efficient fat burning machine when you're doing nothing at all. Vary the intensity you work out at for best results
  • I believe that a calorie burnt by exercising is one less calorie stored in the body and its doesn't make that much difference if its burnt "high" or "low" intensity. You must have to work out pretty hard to burn 20 calories a min, better to have a mix of low intensity and high intensity in the gym. I alway work out in the lower range as I count it as an easy day.

    Running burns the most calories.
  • No - the books are wrong long term. The person burns more fat - yes - but only burns 40% (assuming these percentages are right - highly unlikely). He remains an ineffecient fat burner. He burns more fat that day but loses long term. The other runner burns at 70% (alegedly) becomes a more efficient fat burner and does the faster workout later but burns say 55% fat because they have taught their body to burn fat efficiently. The tortoise beats the hare - watch the big picture!

    Also why put on muscle to burn fat? If you want to burn fat, teach yourself to burn fat with lower intensity runs and then when you have a decent base do more. Be patient. If you want to run fast you don't want extra muscle mass to carry around. Agian, it is true as far as it goes, but that does not make it the best option in the long run.
  • Jane,

    What you say is true to a point, but WHAT calories you burn is as important as how many if:
    1) You want to lose weight long term
    2) You want to run efficiently
    Which I imagine is the whole point of this thread...
  • Hmm. And here's another point. ANY run/waddle/plod/jog for me is high intensity! And I'm sure I'm not alone. :o)

    I'm sure that once I'm a gazelle rather than a wombat I can differentiate between puffing and sweating a bit, and puffing and sweating a lot.

    But for now - I'm just glad I'm burning calories.
  • As I understand it all that matters is that you consume less calories in fuel than you use. Whether its from high intensity or low intensity exercise does not matter.

    While it is true that the body can use fat as the intensity of exercise is gets lower from say 70% of max HR it does not matter that glycogen is used for high intensity exercise as after the exercise the body will break down fat while you rest to replace the glycogen stores. Always provided ofcourse that it does not get it all from eating.

    What is true is that while you are losing weight you will geenrally have lower glycogen levels than you would have normally and hence you will find it difficult to do long high intensity sessions which require glycogen while low intensity would not be a problem as it can be supplied directly from the body's fat stores.

    I have lost 4 stone over three years by doing a mixture of all three approaches in six week bursts with a rest in between coupled with eating a bit less than normal.

    1). High intensity running/cycling/swimming
    2). Weight sessions to build muscle mass (which consumes more calories even when resting)
    3). Quite a bit of walking everyday, between an hour or two at a good pace.
  • Pantman.
    I can run "efficiently" for hours, rubbish at running fast.

    I am prefectly happy with my weight, not skinny, not fat.
  • popsiderpopsider ✭✭✭
    I'd have to disagree with you Pantman, the books are right the gym is wrong (I realise your argument isn't the same as that of the gym which is obviously talking rubbish). I take your point about low intensity but following that to a conclusion you burn a high percentage of calories as fat lying down but that isn't a good way to get thin.

    It's an interesting debate though. Can you spell out your argument in more detail? I take it you are saying steady running causes the body to adapt so that it metabolises fat more efficiently and so will continue to burn a higher percentage fat at higher heart rates? But if that is the case aren't you just using less glycogen - so when you do eat instead of replenishing glycogen stores your body will just lay it down as fat?

    You can probably tell I tend to lean towards the calorific in vs burnt argument.

  • juliejoo,

    too right! Started the same way. Used a HR monitor to r/w/p/j up to a medium intensity and then walked to lower regions of fat burning HR range and then r/w/p/j again - keeps the HR in the right fat burnign range t/out.
  • I think its best just to get a mixture of high and low intensity long term - the low intensity help to build fat burning efficiency and the high intensity burns more fat per workout, which will increase as the low intensity increase fat burning efficiency
  • also, theres nothing wrong with a bit of muscle work to increase endurance and for burning fat, the extra weight shouldn't be a problem unless ur doing way too much weight work or ur putting it on the wrong places
  • Popsider,

    Thanks for an intelligent and thought out response!

    Yes I am saying that teaching your body to burn fat means you will burn it at higher intensities. But to achieve that properly you need to do it EXCLUSIVELY but ONLY for a period. This is similar to what Lydiard was doing and is what many top athletes (who need no weight loss) also do.

    Consider Mark Allen who won the Ironman 6 times (I think) - he never went over a lowish aerobic pulse for 4-5 months of the year! 150bpm , I think it was. Initially he found that to get his pulse that low he was running 7:30 or 8 min mile pace - and this was AFTER he was already one of the "big 4" in triathlon racing at 5:15 pace! He was maxing it out all the time and burn neat carbs! After an extended period of do NO training over 150bpm he managed to get his pace up to 5:30 pace while at that pulse - he taught himslef to burn fat. Anecdotal? Yes, but the science backs it up too.

    The question is short term or long term? If you want to lose weight LONG term, if you want to peak LONG term and if you want to stay healthy LONG term, then fat burning is the way to go.
  • popsiderpopsider ✭✭✭
    Interesting, I suppose the idea of focusing on one thing exclusively would fit in with periodising training - which is popular in lots of sports.
  • Pantman,

    You are getting confused with base training and sharpening (periodising). This is similar to what you have stated, ie, building an aerobic base by doing all running aerobically over *relatively* high mileage for most of your training time, then replacing it with more and more speedwork, but less milage over an 8week period before a race to sharpen. The theory is that after 8weeks of sharpening, you will peak and remain at peak for 3-6weeks depending on whether you are a short or long swing athlete. Although not many "us mere mortal athletes" take the long periods between racing required for proper implementation of base training and sharpening.

    So what you are saying has nothing to do with burning fat. Mark Allen was not doing things that way to burn fat! He was practicing basing and sharpening. Yes, he will learn to burn fat more efficiently at an aerobic pace. But my point is that when you get to the sharpening phase, you can only remain there for a matter of weeks, after that, you must revert back to aerobic training.

    The original question was not about speed, it was about burning fat. I think for fat burning and general fitness, a good all round mixture with most of the training being done aerobically, but with a couple of hard sessions a week, with some weight training is probably the best thing to do for weight loss for most people
  • Well there you go - that was intelligent and well thought-out too, RR. This is an interesting thread...

    (juliejoo settles back with an unintelligent look on her face, trying not to think)
  • RR,

    You say he wasn't doing to burn fat, but HE says he was. By training himself to use fat as his primary fuel source he made himself a better runner. So no I'm not confused.

    The person wanting to lose weight should utilise their fat stores in the same sort of way, rather than "Mens' Health" eclectic approach. Not only will it make a better runner LONG term, but that person can decrease calorific intake without the normal associated tiredness and hunger. They key is the timing of the food.

    The low level of intensity means you can train daily safely and thus increase total calories burned, and you will have far more energy even on a reduced calorie diet.

    It IS the best way to lose weight, fullstop. Almost 2.5 stone in less than 7 weeks with no hunger or tiredness, no loss in muscle mass (slight increase, in fact) and a drop of over 1min/m in speed has proven practically what I already knew theoretically. There is just no way at all that I could have acheived even half of that the "RR" way. Sorry!

    Best wishes to you all from the Pantman (away till Sun ev. now...)
  • ok, ok, I get what ur saying, but what I meant and perhaps was a little obscure was that he wasn't doing it to lose body weight, he was doing it so that he could burn fat more efficiently and build an aerobic base to make him faster. My point was that he was doing it for speed, not weight loss. I don't argue the fact that you lost 2.5stone in 7weeks, and well done for doing so!

    Anyway I'm a stubborn git and if I read something, then something else contradicts it, I tend to believe the first source that I read - probably quite natural! Its certainly an interesting topic and its one that I'm going to read more into before I try and argue black's white - I guess the evidence that I was taking my argument from was from RW and other runners probably as experienced as urself who say that the harder session will increase metabolism for a long time after the workout therefore burning more fat in a workout. But I can see where ur coming from and I'll look into it before getting back with some solid evidence either in one direction or the other....
  • popsiderpopsider ✭✭✭
    I disagree - don't want to go round in circles but purely on the facts of losing weight if you eat more than you use you put on weight (ignoring Atkins type protein overdose stuff). I certainly haven't read any science that would back up what you say but would be interested if you could point me in its direction.
  • And interesting that you mention the Atkins thing, popsider. Would you get a similar training effect to that which Pantman describes by training at whatever intensity but at the same time sticking to a very low carb diet?

    Not something I particularly want to try but perhaps an idea worth exploring.
  • As you may recall, I started this thread.
    I'll freely confess that the numbers that I used were pure fiction, just to get the maths concept across.

    However, the following is a quote from an actual running book:-

    "You may have heard that low-intensity exercise burns more fat than high intensity exercise and therefore think that for weight-loss purposes you are better off running more slowly, in order to get your fat stores down. This is a misconception. The body always uses all types of fuel for all exercise - it's just that the amounts vary, according to the intensity of the exercise. If you exercise for half an hour at a low intensity (say, jogging at 9.5 minute mile pace), you may burn roughly 400 calories in an hour, with approximately 60 per cent [240] of the total calories coming from fat. If you exercised for half an hour at high-intensity (say 8 minute mile pace) you'll burn closer to 700 calories in an hour, but only 40 per cent [280] of the total calories would come from fat. As you can see, you are still burning more calories overall with the higher-intensity workout. And what's more, as you get fitter
    your body will teach itself to utilise more fat in order to conserve its limited carbohydrate stores."

    I've come to the conclusion that there's one reason why I don't lose weight - chocolate!

  • Pammie*Pammie* ✭✭✭
    chocolate's the answer

    and i suppose crisps don't help
  • I'm at my trimmest, slimmest and lightest the day after a race.

    So run very very hard if you want to burn fat.

    BR, sitting here after a particularly satisfying Royal Mixed Kebab and Chicken Korahi and 2 poppadoms, enjoying a bottle of Beaujolais.

    If you want any tips on putting it on again, I'm your man!
  • I've just polished off a huge chicken curry with pop tarts, twixes and a box of After Eights!
  • Carbo and fat loading for something RR?
Sign In or Register to comment.